Synthesis Of Phosphonitrilic Trimer Sulfonate And Its Flame Retardant Effect On Polycarbonate

The flame-retardant modification is a hot spot for the modification of polycarbonate.Although polycarbonate reaches V-2 rating in the UL-94 test,the melt-dripping phenomenon are rather serious,and a large amount of toxic smoke and gases is generated during combustion.Therefore,the flame-retardant modification of PC is very necessary in specific fields such as electric and electronic,architecture,automobile,etc.Hexachlorocyclotriphosphazene is an important intermediate to synthesize halogen-free flame retardants or thermally stable materials.The C1 atoms in hexachlorocyclotriphosphazene can be substituted to synthesize a series of unique phosphazene derivatives.Via the designation of side groups,the nucleophilic substitution reaction between hexachlorocyclotriphosphazene and disodium p-hydroxybenzene sulfonate was conducted.A novel halogen-free flame retardant——HPCP-SS was synthesized.FT-IR and NMR were utilized to characterize the structure of HPCP-SS and it was proved to be synthesized successfully.The TGA results show that the initial decomposition temperature of HPCP-SS was 269.4?,which is higher than the processing temperature of PC(180-220?).Hence HPCP-SS can be used as flame retardant stably.It shows that HPCP-SS can improve the flame retardancy of PC significantly.With the addition of 0.04wt%of HPCP-SS,PC/HPCP-SS composites can reach V-0 rating in the UL-94 test.When the loading of HPCP-SS reached 0.06wt%,the limiting oxygen index(LOI)will increase from 24.9%to 31.1%.Via the use of TG-IR,SEM,Raman spectroscopy,cone.etc,the structure,morphology and properties were studied.It was found that total thermal release and total smoke release were decreased to some extent.At the mean time,toxic gases produced like CO and total oxygen consumed decreased a lot.And small aromatic compounds and hydrocarbons decreased due to the catalytic charring effect of HPCP-SS.More compact and dense char layer was formed and hence blocked the oxygen and the attack of heat.The sulfonate for the flame retarding of PC is rather efficient and the loading is very small.DSC curves of PC/HPCP-SS composites suggest there were no significant change in the crystallization process as well.Hence the addition of HPCP-SS will cause no signifant influence to the transmittance and the mechanical properties of PC.